Ground-based spectral solar radiance and irradiance measurements are important for i) validation of satellite measurements in the respective wavelength bands, as e.g. MODIS, and for ii) detailed studies about the temporal (diurnal, seasonal, interannual) variation of the shortwave radiation.
The Institute of Oceanography (IfM) of the University of Hamburg carried out ground-based spectral radiance and irradiance measurements at the research site Cape Verde Atmospheric Observatory (CVAO) Humberto Duarte Fonseca from March 2008 through October 2015. The observatory is located at 16°51'50.43" N, 24°52'3.67'' W close to the village Calhau at the northeastern coast of the island Sao Vicente of the Capverde Islands. The distance of the observatory to the shore is about 50 m, the altitude of the observatory is about 10 m above m.s.l.
For the UV/VIS radiance measurements two hyperspectral UV-VIS radiance sensors are used (RAMSES-ARC from TriOS); one in a standard configuration and one equipped with a grey filter to enhance the intensity range. For the UV/VIS and UVA/UVB irradiance measurements a hyperspectral UV-VIS irradiance sensor (RAMSES-ACC-VIS) and UVA/UVB irradiance sensor (RAMSES-ACC-UV) are used (also both from TriOS). Measurements were carried out between 6:00 UTC and 22:00 UTC every day with 5 minute sampling. The wavelength range is 320 to 950 nm (280 to 500 nm for the UV sensor).
The SOPRAN RAMSES Radiometer data set was included into the ICDC data base on March 24, 2016.